D.-c. timing device



Oct. 20, 1959 R WITTE 11-0. TIMING DEVICE 4 Sheets-Sheet 1 Filed May 17, 1957 /NVENTO/-? ROY W/TTE Oct. 20, 1959 R. WlTTE D.-c. TIMING DEVICE Filed May 17. 1957 4 Sheets-Sheet 2 F/ai' INVENTOR ROY W/TTE ATTY Oct. 20, 1959 R. WITTE 2,909,029

D.-C. TIMING DEVICE Filed May 17, 1957 4 Sheets-Sheet 3 Elf/7075A. Y l I (WWI/MALE INVENTOR.

DEV/CE M ROY W/ TTE ATTY Oct. 20, 1959 R. WITTE 11-0. TIMING DEVICE 4 Sheets-Sheet 4 Filed May 17, 1957 INVENTOR ROY W/TTE ATTK United States Patent D.-C. THVIING DEVICE Roy Witte, Whea'ton, Ill., assignor to General Time Corporation, New York, N.Y., a corporation of Delaware Application May 17, 1957, Serial No. 659,912 8 Claims. (Cl. SS-41) The present invention relates to timing devices and more particularly to a D.-C. operated timing device for generating accurately timed electrical impulses.

D.-C. timing devices in common use, for example, as vehicle clocks, are conventionally powered by an armature which is picked up periodically by an electromagnet, serving to wind a short-term spring whenever the armature retrogrades to its unwound position, the cycle being on the order of several minutes in length. Such devices are usually capable of starting automatically when voltage is reapplied following disconnection, since the contacts are left in the closed condition when the mechanism is completely run down. However, the winding cycle cannot be utilized for timing purposes since the period varies in accordance with changes in voltage and other extraneous factors. Another type of D.-C. timing device known in the art includes provision for winding periodically under the control of the timing train, which provides a more precise timing cycle; however, such devices have been subject to a number of disadvantages.

It is an object of the present invention to provide a D.-C. timing device which is capable of putting out an accurately timed series of impulses, for example, once per minute, for control purposes and which is so arranged as to insure positive and immediate restarting when voltage is reapplied following a sustained interruption of the normal power supply line. It is a general object to provide a D.-'C. timing device which is not only accurate but which is reliable in applications subject to possible or frequent interruption in electric power. It is moreover an object to provide a D.-C. timing device which starts dependably when voltage is reapplied following a long interruption as, for example, incident to use in a guided missile or other apparatus which must be stored for long periods of time under standby conditions.

It is another object of the invention to provide a D.C. timing device of the type described in which a single set of contacts serves both to wind the device and to generate accurately timed control impulses for synchronized operation of various slave devices.

-It is a further object of the present invention to provide a D.-C. timing device which is inherently simple and which may be added as an improvement to existing designs of D.-C. timers and clocks, for example, vehicle clocks.

It is still another object of the present invention to provide a D.-C. operated device for generating timed impulses and which may be constructed for any desired degree of accuracy using parts of the type conventionally employed in the clock art and without adhering to unusually exact tolerances in manufacture or assembly. It is a related object to provide a timing device which may be manufactured inexpensively on a quantity production basis and which will operate reliably over long periods of time even in the face of the shock and vibration encountered in rough military and commercial usage. Other objects and advantages of the invention will be- ICC come apparent upon reading the attached detailed description and upon reference to the drawings in which:

Figure 1 is a front view of a timing device constructed in accordance with the present invention with the minute and hour hands and the gearing usually associated therewith omitted.

Fig. 2 is a top view of the device shown in Fig. 1.

Fig. 3 is a fragmentary top view of the contact arms taken along the line 33 in Fig. 1.

Fig. 4 shows the electromagnet and armature construction taken along the line 44 in Fig. 2.

Fig. 5 is an end view corresponding to Fig. 4.

Fig. 6 is a distorted perspective of the mechanism for facilitating an understanding of the operation.

Figs. 7a-7d are diagrams showing a typical winding cycle under ordinary operating conditions.

Figs. 8a8e are diagrams showing the running down of the mechanism upon disconnection of power and the automatic restarting when power is reapplied.

Figs. 9a9c are diagrams showing the operation of the latch mechanism.

While the invention has been described in connection with a preferred embodiment, it will be understood that I do not intend to be limited to the embodiment shown, but intend to cover all alternative and equivalent constructions falling within the spirit and scope of the appended claims.

Turning now to the drawings, there is shown a mecha nism embodying the invention which may, for conveni ence, be considered as three sub-assemblies, namely, a motor portion 11, a timing train 12 and a switching arrangement 13, energized by a battery 14 and cooperating to produce timed impulses in a control line 15. Minute and hours hands, and the gears which couple them, have been indicated diagrammatically at 16, 16a, it being understood that the present device is primarily intended for the purpose of producing precisely timed voltage impulses and that addition of hands for display purposes constitutes a useful but optional feature.

It is convenient to give consideration first to the timing train. Such timing train includes an input gear 20, which is kept under torsion by the motor portion 11. Meshing with the input gear 20 is a pinion 22 directly coupled to a gear 23. Compound reduction is effected by a pinion 24 meshed with the gear 23 and rigidly connected to a gear 25. To cause rotation of the driving train at a timed rate, an escapement of conventional type is employed including an escapement wheel 30 having a pinion 31 mesh ing with the gear 25. Cooperating with the escapement Wheel is a verge 32 having pallets 33 and a forked arm 34. The arm engages a balance wheel 35 having an associated hair spring 36. Thus, as long as torque is applied, rotation of the train will occur at a timed rate. A shaft 40 connected to the gear 23 serves as the output shaft, and it is to this shaft that the indicating hands, in dicated at 16, may be coupled with appropriate gearing (Fig. 6).

For the purpose of applying torque to the input of the driving train, the motor portion 11 includes an electromagnet having coils 41, 42 which are connected in series with one another and provide oppositely-poled pole pieces 43, 44. Arranged in front of the coils 41, 42 and centrally pivoted for oscillation in a plane parallel to them is an armature 46 having a shaft 47. For the purpose of tensioning the armature 46 in a retrograde direction, i.e., away from the pole pieces, a coil spring 43 is provided. This spring may be referred to as a short term spring since it need only store enough energy to drive the mechanism for a period of two minutes or so. Moreover, to permit free winding movement of the armature when the electromagnet is energized, a one-way force transmitting coupling is employed. The latter consists of a ratchet wheel 50 having a serrated edge engaged by pawls 51, 52 mounted symmetrically on the armature, such pawls being provided with suitable springs to keep them in engagement with the wheel 50. And to prevent movement of the wheel 50 during the winding operation, a keeper pawl 53 is used which is pivoted to the frame and which also has a suitable spring for keeping the teeth thereof in engagement with the wheel. It will be understood as the discussion proceeds that the pawl 53 clicks idly during the time that the armature rotates clockwise under the influence of the coil spring 48.

For the purpose of coupling the ratchet wheel 50 to the gear of the driving train and for insuring that torque continues to be applied to the timing train even during the winding interval, a coil spring 55 is used having its ends anchored in the members 20, 50, and sandwiched concentrically between them. With regard to the operation of the device, as thus far described, it will be apparent that energization of the electromagnet causes the armature 46 to be attracted in a winding or counterclockwise direction, with. clicking taking place at the pawls 51, 52 and accompanied by tensioning of the return coil spring 48. During winding, the ratchet Wheel 50 is blocked by the pawl 53 and the energy previously stored in the auxiliary spring 55 continues to supply torque to the timing train. Following the winding operation, the coil spring 48 urges the armature clockwise, resulting in timed rotation of the output shaft 40.

' In carrying out the present invention, a switch coupled to the output shaft 40 is provided for energizing the electromagnet at precisely spaced intervals of time, such intervals being sufliciently short so that the energy stored by the armature during a single winding operation is more than sufficient to drive the timing train through a single interval. In the presentembodiment, the momentary making of contact is brought about by a saw toothed cam 60 mounted on the end of the shaft 40 and engaged by contact arms 61, 62 having contacts 61a, 62a. The contact arms 61, 62 are mounted at their base in a suitable insulating support 63 so that their tips 61c, 62c ride side by side on the surface of the cam 60. The arm 61 is preferably a few thousandths of an inch shorter than the arm 62 so that as the saw toothed cam 60 rotates, the

' arm tip 610 drops, followed, after a short time interval on the order of two seconds, by the arm tip 62c. The arms are so constructed and arranged that contact is made during this two second time interval, as is set forth in the sequential diagram, Figs. 7a-7d, to which reference is made,

tin these figures, Fig. 7a represents the fully wound condition while 7b shows the position of the armature and switch arms a half minute or so thereafter. Upon further unwinding, switch arm 61 drops from a lobe of the saw toothed cam, bringing the contacts together and causing the armature to be attracted and restored to its wound position. Two seconds later, the continued rotation of the cam causes the arm 62 to drop off into the position shown in Fig. 7d where the contacts are separated, thereby to begin a new cycle of timed operation.

Since the contacts arein the open condition 58. seconds of each minute, the probabilities are that the contacts will be in the open condition when the device completely runs down due to disconnection of the power source as, for example, upon changing the supply battery. Consequently, when power is reapplied, the electromagnet will be open circuited and will not pick-up automatically to restart the timing mechanism. In accordance with the present invention, a set of auxiliary contacts is provided in shunt with the normal contacts, together with means for making contact whenever the armature reaches its fully unwound or retrograde position. In the present embodiment, the auxiliary contacts are indicated at 71, 72, respectively, the contact 71 being formed integrally with, and in the plane of, the contact arm 61 (see Figs. 3

4. and 6) the contact 72 being secured to an auxiliary contact arm 73. Such contact arm is pivoted at a pivot 74 and has a tip portion 75 which is arranged in the path of movement of the armature. Electrically, the contact 72 is mounted on a depending insulated bracket 76 secured to the arm 73 and the contact is moreover connected to the contact arm 62 by means of a pig-tail 77. Under normal running conditions, the arm is biased downwardly by means of a spring 78 and rests against a stop 79, the contact 72 thereon thus occuping an out-of-the-way position. 7 r

The function of the auxiliary contacts 71, 72 will be apparent upon reviewing a typical disconnect cycle as set forth in Figs. 8a-8c which shows the position of the contact 72 at various points in such cycle. In Fig. 8a, the armature is partially unwound :and the contact arms are approaching drop-off. Assuming that the power source has been disconnected, when drop-off occurs as shown in Fig.

' 8b, the contacts will close but there will be no resulting rewinding of the armature. Since the energy stored in the spring 48 is more than sufficient for a single cycle of operation, the saw toothed cam 60 will continue its timed rotation. The additional movement of the armature which occurs thereafter causes the auxiliary arm 73 to be picked up, thereby advancing the contact 72 upwardly as shown in Fig. 80. When the device comes to rest with the armature in its completely unwound position, firm contact is assured between the movable contact 72 and contact 71 on the switch blade 61. Consequently, when power is reapplied, the circuit is closed through contacts 71, 72 to re-energize the electromagnet causing the armature to rotate to its wound position. This movement is accompanied by downward movement of the arm 73 under the influence of the spring 78, thereby breaking the circuit of the electromagnet and restoring the contact 72 to a lowered out-of-the-way position. It will be apparent that with the armature thus wound, the regular contacts 61a, 6201 will be effective to cause periodic energization of the electromagnet.

Further in accordance with the present invention, means are provided for temporarily disabling the normal contacts for a predetermined time interval following reapplication of voltage after a sustained interruption of electric power. in order to insure that torque is applied to the driving train even in the event that the mechanism should run down and come to a rest with the cam in the position shown in Fig. 8d, pick-up will occur by reason of contacts 71, 72 as described above. However, the resultant lowering of the auxiliary arm 73 will, under such conditions, cause contact 61a to be lowered into engagement with contact 62a, thereby causing a sustained current to flow through the electromagnet. With current flowing through the electromagnet, the armature 46 is held immobile, thus preventing torque from being applied to the driving train by the coil spring 48. Under re-start conditions, there is no torque in the auxiliary spring 55 and consequently, no movement of the driving train so that the mechanism will simply hang-up and fail to begin its regular timing cycle. 7

Accordingly, my invention contemplates the providing of a latch mechanism for latching the regular contacts 61a, 62a so that they cannot come together when voltage is reapplied following a sustained power interruption,

which latch mechanism is effective whenever the cam 60 is in that phase of its cyclewhere contact is normally made between the contacts 61a, 62a. More specifically, I provide a latch member which is cycled by the saw toothed cam 60 so as to be brought into latching position whenever the switch arms 61, 62 are in the vicinity of their drop-off positions relative to the cam. When the latch member 90 is active, a tip 91 thereon is in overhanging position relative to the tip of the switch arm 61. Moreover, the tip 91 of the latch member is so spaced above the arm 61 that the tip of the arm 61 tends to wipe past the latch member into latching position when lifted by the auxiliary contact 72 incident to complete run down of the armature 46. For the purpose of oscillating the latch member 90 back and forth between its active position and its inactive position, such latch member includes a cam follower portion 92 riding on cam 60.

The operation of the latch member will be apparent upon reference to a typical cycle of latching operation set forth in Figs. 90-90, where it will be assumed that the cam is so phased that at complete run-down, the cam occupies its contact-making position, i.e., with the arm 61 in position to re-establish contact with the cooperating arm 62. Such condition, as stated, exists only during two seconds out of each minute and thus the odds against this condition are about 30:1. Nevertheless it is a possible con dition and must be accounted for. Referring more specifically to Fig. 9a, it will be noted that the latch member 90 is in its active position and that the switch arm 61 has wiped past the tip 91 thereof into latched or blocking position. The position which the arm 61 would occupy, but for the latch and but for the contact 72, is indicated by the dotted line. Upon reapplication of voltage .after a sustained interruption, current flows through contacts '71, 72 as described above to energize the electromagnet, causing the contact 72 to be lowered into the position shown dotted in Fig. 9a. This lowers the arm 61 onto the latch 90 but because of the latch the arm 61 is maintained in its out-of-contact position. This insures that the electromagnet is, after its initial energization, de-energized, and consequently the armature 46 is free to apply torque to the input gear 20 of the timing train. Upon passage of a few seconds of time, Fig. 9b, rotation of the cam 60 occurs thereby allowing arm 62 to drop off, the arm 61 remaining latched. Upon further passage of time, Fig. 9c, the latch 90 is cammed to its left-hand or inactive position and allowing the switch arm '61 to be lowered into'its normal running position.

Since by this time, the critical two-second interval during which contact is normally made is safely past, the device will continue to cycle in the normal way previously discussed in. connection with Figs. 7a7d.

It will be apparent from the foregoing that the device is capable of re-starting positively upon reapplication of power regardless of the phasing of the mechanism, and particularly the phasing of the-cam '60, at the time that final run-down occurs.

Since periodic contact is made at the output of the timing train, such contact is entirely under the control of the escapement mechanism and consequently can be caused to occur with any desired order of accuracy. This is particularly true since each lobe of the cam occupies A; of a full circle; consequently appreciable movement, or at least detectable movement, takes place at the cam 60 during an interval of time as short as one second. Provided that the cam is accurately formed with sharp edges, the drop-off may be made consistent in timing from lobe to lobe. If still further accuracy is desired, the size of the cam or the arcuate length of the lobes may be increased. For example, a four lobed cam could be employed, operating at a speed of r.p.m. This is a matter which is well within the skill of the art.

The accuracy and reliability of the present arrangement causes it to be particularly well adapted for use in precision devices where a remotely controlled device, such, for example, as indicated at 90 in Fig. 6, must be impulsed at regular intervals. It is particularly noteworthy that a single set of contacts sufiices for both winding up the armature and for controlling the remotely controlled device, thereby making it unnecessary to secure synchronization by separate sets of contacts. The remotely controlled device may, for example, consist of a slave clock or timer.

The above, it will be noted, has been accomplished using standard parts of a type normally employed in an automobile clock or the like; consequently, the construc- 6 tion is durable and susceptible to inexpensive production line manufacture.

Where the device described above is used in an automobile, it may be placed in an out-of-the-way position under the hood and slave clocks, for example, of the type employing a simple electromagnetic ratchet may be mounted in the dash and also in a convenient back seat position. Since the slave clocks may be made silent in operation, any noise arising from the use of the present clock system as may be caused, for example, by the periodic winding of the armature is isolated under the hood of the automobile.

I claim asmy invention:

1. In a timing device for use with a D.-C. voltage source, the combination comprising a timing train having an input and an output togetherwith an escapement, an electromagnet, a spring biased armature cooperating with said electromagnet for tensioning said spring when the electromagnet is momentarily energized, a ratchet mechanism for coupling said armature to the input of the timing train, a switch operating cam coupled to the output of said timing train, contact members having cooperating electrical contacts thereon electrically connected to said electromagnet, said contact members being so arranged with respect to said cam that momentary contact takes place periodically incident to cam rotation, the rate of movement of said cam being such as to cause said momentary contact to occur when the armature has undergone only a portion of its retrograde movement, and auxiliary contact means connected to said electromagnet and so arranged as to make contact when said armature is at its limit of retrograde movement thereby to eflect restarting of the mechanism when voltage is reapplied to the device 1 following a sustained interruption.

2. In a timing device for use with a D.-C. voltage source, the combination comprising a timing train having an input and output together with an escapement, an electromagnet, a spring biased armature cooperating with said electromagnet for tensioning said spring when the electromagnet is momentarily energized, a ratchet mechanism for coupling said armature to the input of the timing train, a switch operating cam coupled to the output of said timing train, contact members having cooperating electrical contacts thereon electrically connected to said electromagnet, said contact members being so arranged With respect to said cam that momentary contact takes place periodically incident to cam rotation, and means operated incident to said armatures approaching its limit of retrograde movement for completing a shunt circuit around said contacts, thereby to effect restarting of the mechanism When voltage is reapplied to the device following a sustained interruption.

3. In a timing device for use with a D.-C. voltage source, the combination comprising a timing train having an input and an output together with an escapement, a short term spring coupled to the input, an electromagnet, a ratcheted armature cooperating with said electromagnet for tensioning said spring when the electromagnet is momentarily energized, a saw toothed cam coupled to the output of said timing train, contact members having cooperating electrical contacts thereon riding on said saw toothed cam and so arranged that the arms drop off of the lobes of the cam in closely spaced sequence with contact being made during the sequence interval, and means including auxiliary electrical contacts operated incident to the arrival of said armature at its limit of retrograde movement for completing a shunt circuit around said contacts, thereby to insure restarting of the timing train when voltage is reapplied to the device following a sustained interruption.

4. In a timing device for use with a D.-C. voltage source, the combination comprising a timing train having an input and an output together with an escapement for controlling the rate of the output, a short term spring coupled to the input, an electromagnet, means including an armature cooperating with said electromagnet for winding said spring when the electromagnet is momentarily energized, a saw toothed cam coupled to said output,-switch arms riding side by side on said saw toothed cam and dimensioned for drop-off in rapid sequence, said switch arms being so constructed and arranged that contact is made between them only during the sequence interval, auxiliary contact means having contacts 'arranged in shunt with said switch arms for making contact incident to said armatures reaching the limit of its retrograde movement for energizing said electromagnet when voltage is reapplied following a sustained interruption, and means for disabling said normal contacts for a predetermined time interval following an interruption of electrical power.

5. In a timing device for use with a D.-C. voltage source, the combination comprising a timing train having an input and an output together with an escapement for controlling'the rateof the output, a short term spring coupled to the input, an electromagnet, means including an armature cooperating with said electromagnet for winding said spring when the electromagnet is momentarily energized, a saw toothed cam coupled to said output, switch arms riding side by side on said saw toothed cam and dimensioned for drop-ofl. in rapid sequence, said switch arms being so constructed and arranged that contact is made between them only during the sequence interval, auxiliary contact means having contacts arranged'in shunt with said switch arms for making contact incident to said armatures reaching the limit of its retrograde movement for energizing said electromagnet when voltage is reapplied following a sustained interruption, and a latch adjacent said contact members for temporarily holding the contact members out of engagement with one another following operation of said auxiliary contact means.

6. In a timing device'for use witha D.-C. voltage source, the combination comprising a timing train having an input and an output together with an escapement for controlling the rate of the output, an electromagnet, a spring biased armature cooperating with said electromagnet for winding said spring when the electromagnet is momentarily energized, switch means coupled to said output for periodically connecting said electromagnet to said voltage source for periodic winding of said spring prior to said armatures reaching its limit of retrograde movement, auxiliary means for closing an electrical circuit to said electromagnet incident to said armatures reaching its limit of retrograde movement thereby to insure restarting upon reapplication of voltage following sustained interruption at said voltage source and means for disabling said switch'means fora predetermined fin: terval'following' s'aid reapplication' of voltage. 7Q In a timing device for use 'with .a D.-C. voltage source, the combination comprising a timing train having an input and an output together with an escapement for controlling the rate of the output, an electromagnet, a spring biased armature cooperating with said electromagnet for winding said spring when the electromagnet is momentarily energized, switch means including a cam coupled to said output for periodically connecting said electromagnet to said voltage source for periodic winding of said spring prior to said armatures reaching its limit of retrograde movement, auxiliary means for closing an electrical circuit to said electromagnet incident to said armatures reaching its limit of retrograde movement thereby to insure restarting upon reapplication offvolta'ge following a sustained interruption at said voltage source, and means operated by said cam for disabling said switch means fora predetermined time interval following said reapplication of voltage.

8. In a timing device for use with a D.-C. voltage source, the combination comprising a timing train having an input and output together with an escapement for controlling the rate of the output, an electromagnet, a short term spring, an armature cooperating with said electromagnet and connected to said spring for tens'ioning said spring when the electromagnet is engaged, means for coupling said armature to the input of said timing train so that the armature moves toward retrograde position incident to passage of time, contact means coupled to the output of said timing train for making contact periodically during the operation of the latter, auxiliary contacts in shunt with said periodic contact means, and means including a member engaged by said armature as the latter moves intoits fully retrograde vposition for closing said auxiliary contacts and for temporarily disabling said periodic contact means so that said armature is wound by said electromagnet upon reapplication of voltage following a sustained interruption thereof while insuring that the circuit of said electromagnet is broken immediately following the closure of the auxiliary contacts.

References Cited in the file of this patent UNITED STATES PATENTS 

